Mounting for player arms



' March 13, 1951 w KEN'NEY 2,545,353

MOUNTING FOR PLAYER ARMS Filed April 21, 1947 Patented Mar. 13, 1951 MOUNTING FOR PLAYER ARMS Mahlon W. Kenney, Oak Park, Ill., assignor to J. P. Seeburg Corporation, Chicago, 111., a corporation of Illinois Application April 21, 1947, Serial No. 742,924

4 Claims. (01. 274-23) This invention relates to player arms or tone arms for phonographs. These arms require pivotal supports on two axes. One arm is parallel to the turntable axis to permit movement of the pickup across the record as the stylus follows the groove. The other axis is at right angles to the first mentioned axis to permit movement of the stylus away from and towards the record. This second axis enables the player arm to be raised from, and lowered to the record, either manually or automatically, and also provides for vertical movement of the pickup during the playing of a record.

bearing amounts to between four and nine grams,

measuredat the needle, and is seldom less than four grams. In the case of a pickup having a low nominal needle pressure, for example, around one ounce or one-half ounce, the needle pressure actually varies by a large percentage. This results in excessive wear on the record grooves and failure of the stylus to follow the record groove perfectly with resultant distortion in the audible reproduction. Furthermore, the. loose fit of the bearing permits vibration of the player arm in its plane parallel to the record, thus introducing further distortion into the audible reproduction. V

In accordancewith the present invention, I provide for the vertical movement of the player arm, a knife edge pivot. This knife edge pivot cooperates with members providing V-shaped recesses. In order to insure a perfect V-shaped recess, I employ two adjacent strips cut obliquely in opposite directions. It is easy to obtain a straight edge on a strip and that is all that is necessary to obtain a perfect V-shaped recess.

In the embodiment of the invention hereinafter described and illustrated, I provide the elements constituting the V-shaped recesses on the player arm and the knife edge on the element which pivotally supports the player arm. It must be understood however, that this relation may be reversed in accordance with the present invention.

The present invention will be readily understood from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings in which:

Figure 1 is an inverted plan view of a player arm embodying my invention;

Fig. 2 is a fragmentary sectional elevational view therethrough, taken on the line 22 of Figure 1;

Fig. 3 is an elevational view of the knife edge member;

Fig. 4 is a perspective view of the elements providing the V-shaped recesses, and associated elements; and

Fig. 5 is a perspective of a. clamping member employed in the assembly.

Referring to the drawings, the reference numeral It designates the player arm, which carries a pickup ll, including a stylus l2. The player arm I0 is pivotally supported on a support l3 which is integral with a sleeve M. The sleeve i4 is pivotally supported in a vertical standard [5 so as to'provide the vertical axis for the movement of the player arm across the record. Where the player arm is employed in an automatic phonograph or record changer, the player ,arm may be raised, in known manner,

,by a pin I6 which extends through the sleeve 'ried by the player arm Hi.

The V-shaped recesses are established by two U-shaped elements 22 and 23, dimensioned so that the member 22 fits into the member 23 as shown in Fig. 4. The legs of the members 22 and 23 are provided with oblique edges 2 and 25 which intersect when the member 22 is assembled within the member 23. The members 22 and 23 are rigidly mounted on the player arm It so that the V-shaped recesses are directed downwardly to cooperate with the ends of the knife edge member 28 carried by the support l3, as shown in Fig. 2. The player arm i0 is provided with depending shouldered elements 26 which provide four corner supports for the U-shaped members 22 and 23. Preferably, the bases of the U-shaped members 22 and 23 means of a screw 3| and it is provided with two,

legs 32 and 33 which extend below the arms 2| of the knife edge member 2|] when the clamping member is assembled on the player arm.

Between each pair of depending shouldered elements, I provide recesses 35, so that the ar ms 2! of the knife edge member may project beyond the members 22 and 2 3. An abutment 35 on the support i3 is arranged to engage a shoulder 36 on the player arm to limit the. downward movement of the player arm. The weight of the player arm may be counterbalanced to give the desired needle pressure by means. of a spring 31' which is connected to an arm 38 rigid. with the support 13, and to the player arm In. This spring may suitably. be connected to thev washer 28- and I- provide a'slot 39. in the. post 2?. to accommodate the upper end of the spring. The adjustable screw [1 may suitably be carried by a nut 60 carried by the clamping member 30 As indicated: by the dot and dash lines in Figure 1, the axis provided by the knife edge member 26 is substantially at right angles to the longitudinal direction of the pickup and stylus. Consequently, the player. arm can cooperate with records on the turntable at various elevations without substantial displacement of the pickup about its-longitudinal axis.

My improved-player arm has a practically geometrically perfect bearing. It has substantially zero friction. The friction cannot be detected with the instrumentswhich indicate between four and nine grams with conventional bearings. The spring 31. assists the Weight of the-player arm. in keeping the knife edge seated in the V--shaped recesses provided bythe edges 24 and 25'. Since these recesses are geometrically perfect, the player arm is precisely mounted relative to the member 3 l so that the stylus always lands on the record at correct initial position when the player arm is incorporated in an automatic phonograph-L Although the invention has been described in connection with the specific details of a preferred embodiment thereof, it must be understood that the invention is not intended to be limitative to such details except insofar as set forth in the accompanying claims.

Having thus described my'invention, I declare that what I claim is:

1. In a player arm assembly for phonographs comprising a player arm element and a supporting element carrying said player arm element, in combination, a knife edged member carried by one element, a pair of U-shaped members, and means securing said U-shaped members to the other element in nested relation, the adjacent legs of the Lieshapegl members having relatively oblique edges which intersect in said nested relation to provide V-shaped recesses for the reception of said knife edged member.

2;. In a player arm assembly for phonographs comprising a'player arm element and a supporting element carrying said player arm element, in combination, a knife edged member carried by one element, a pair of U-shaped members, means securing; said lleshaped members to the other element in nested relation, the adjacent legs of the U -shaped members having relatively oblique edges which intersect in said nested relation to provide V-shaped recesses for the reception of said knife edged member, and means carried by said other element extending across said knife edged member to retain it in said recesses.

3. In a player armassembly for phonographs comprising-a player arm and-a supporting member carrying said playerarm, in combination, a knife edged member carried by said supporting member, and a pair of U-shaped members, and means securing said U-shaped members to the player arm in nested relation, the adjacent legs of the U-shaped member having relatively oblique edges which intersectin said nested relation to provide V-shapedrecesses for the reception of said knife edged; member.

4. In a player arm assembly for phonographs comprising a player arm and a supporting membercarrying said playerarm, in combination, a knife edged member carried by, said sup rting member, a pair of U-shapedmembers, means securing said U shapedmembers to the player arm in nested relation, the adjacent legs of the U-shaped members havingrelatively oblique edges which; intersect in saidnested relation to provide V-shapedrecesses for the reception of said knife edged member, and mean carried by the player arm extending across saidknife edged member to retain it in saidrecesses.

MAHLON W. KENNEY.

REFERENCES CITED The following references,are of record, in the file o th s patent; 

